Polyphemus Moth

The Polyphemus Moth (Antheraea polyphemus), is a member of the Saturniidae (giant silk moths) family. It is a tan colored moth, with an average wingspan of 6 inches. Its most noticeable feature is the large purplish eyespots on its two hind-wings. The eyespots are where the moth gets its name – from the Greek myth of Cyclops Polyphemus. The caterpillar of the Polyphemus moth can eat 86,000 times its weight at emergence in a little less than two months.

The life cycle of the moth is much like that of any other Saturniidae species. It lays flat, light brown eggs on the leaves of a number of host plants, including birch, willow, oak, maple, hickory, beech, walnut, various fruit trees, and elm. When the eggs hatch small yellow caterpillars emerge. As the caterpillars age, they molt 5 times. Each instar is slightly different, but on their sixth and final instar they become a bright green color with silver spots on their side. They feed heavily on their host plant and can grow up to 3-4 inches long. They then spin cocoons of brown silk, usually wrapped in leaves of the host plant.

There are generally two broods throughout the United States, one that hatches in early spring and one that hatches in late summer. The moths enclose and then must pump their wings with fluid (hemolymph) to extend them. The females emit pheromones, which the male can detect through its large, plumose antennae. Males can fly for miles in order to reach a female. After the moths mate, the female spends the majority of the remainder of her life laying eggs, while the male may mate several more times. Adults of this family of moths have vestigial mouths, meaning their mouth parts have been reduced. Because of this, they do not eat and only live as adults for less than one week.

Differentiating between sexes of this species is very easy. The most obvious difference is the plumose antennae. Males will have a very bushy antenna while females will have a moderately less bushy antenna. Another difference is that the females will be slightly larger in the abdomen due to carrying eggs. There is a surprising amount of variation within this species. Color patterns can range from a reddish-cinnamon to a dark brown but are almost always a shade of brown.